Photographic printing apparatus



April 18, 1944. E. B NOEL IHOTCC-HATU.C PRINTING APPARATUS Filed March18, 1941 Inventor: I Edw rd B. Noet,

His Affor'neg.

Patented Apr. 18, 1944 I 2.34am rno'roanarnlc ramrmo APPARATUS Edward 3.Noel, Cleveland Heights, Ohio, assignor to General Electric Company, acorporation. of

New York Application March 18, 1941; SerialNo. 383,975 (Cl. 95-73) 9Claims.

The recent development of photographic print ing papers in which theeffects of either soft or hard papers are obtained from a singleemulsion by varying the color content of the light used for exposure(Photo Technique, October, 1940, p. 59- v Rowland S. Potter) has givenrise to a need for a light source in which the relative percentages ofthe various color components may be varied at will and pre-set at anypredetermined desired values before the exposure is made. It is anobject of the present invention to provide a printing apparatusincorporating a source of light, the color composition of which may beconveniently and readily varied in the aforesaid manner. Further andother objects and advantages of the invention will be apparent from thefollowing detailed description and from the accompanying drawing inwhich like numerals indicate like parts throughout and in which Fig. 1represents apparatus embodying the principles of the invention, whilethe Fig. 2 represents an alternative modifi cation of the arrangementshown in Fig. 1.

Referring to Fig. 1, the apparatus there shown comprises generally of atleast one lamp l concentrically surrounded by a rotatable, cylindricalfilter II which is composed of a pair of semicylindrical sections l2 and13 of different colors. For example, the semi-cylindrical section l2 maybe minus blue (a type of yellow filter) and the section 13 minus red (9.type of blue filter). After passing through the filter, the light fromthe lamps l0 goes through the ground glass diffusing plate H whichrenders the illumination on the photographic printing plate or negativel5 uniform. By rotating the cylinders I l to any de- ,sired angularposition, the color of the light which passes through the ground glassto the plate l5 may be given any relative percentage composition of thelight from sections l2 and I3 varying all the way from 100% minus redwhen the filter I3 is in the downward position, to 100% minus blue whenthe filter [2 is in that position. The lamps It may consist of any ofthe sources of "white, or

daylight illumination which are available inthe Alternatively, the lampsmay comprise a clear glass tube in which a gaseous discharge capable ofemitting radiation which excites a fluorescent material is operated. Inthat-case, the sections l2 and I3 may comprisesemi-cylindrical glasswalls upon which fiuoresjcentmaterials capable of emitting thecorresponding colors may be coated. I

For the purpose of rotatin' the members H to the desired positions, agear system indicated generally by the numeral limay' beprovided. Thegear system may comprise *a series "of driving gears I! which cooperatewith. the sprockets l8 positioned on the ends'of the members H, a set ofidler gears I! being provided so that the motion of each of thedrivinggears is in the same direction. The filter members II will rotatein the trough formed between the'driving gears. The whole system may berotated by a suitable knob 20 provided on the shaftof the left-handdriving gear H, the scale 2| being provided for the purpose ofcalibrating the rotation of the filter members in terms of the colorcomposition of the light reaching the photographic plate. The variousmembers of the system may be supported by any suitable means. Forexample, the lamps ID are supported by the bracket 22 and the sockets 23appended thereto, while the gears l1 and is are supported by the bracketindicated generally by the numeral 24. The lamps l0 may be energized byany suitable source of electric power (not shown).

Referring now to the alternative modification shown in Fig. 2, the lampIII in this case is housed within a reflector 25 which may be parabolicin form or of any form which will direct the rays of the lamp I0 towardthe diifusing plate i4 andthe photographic plate IS. The filter membersmay take the form of the series of interlocking orthogonal vanes 26 and21, the vanes 26 being of one color such as minus blue, and the vanes 21of a second color such as minus red. For. the purpose of rotating thevanes 26 and 21, a gear system Ilia similar to that of Fig. 1 maybeproart, or any polyehromatic source capable of emitting at least thecolors'which pass through'the filter. For example, they may take theform of an incandescent lamp or a fluorescent gaseous discharge tube ofthe type shown in the U. 8.

Patent 2,182,732 to Meyer, et al. The discharge tube in the latter casemay be coated with a fluorescent material which produces polychromaticlight having the desired colors as components.

vided. Similarly, the knob 20 and the dial 2| may be provided forthepurpose of setting the rotation of the vanes and for calibrating therotation thereof. The operation of the vane system will be generallysimilar to that of Fig. 1. When the system is rotated to the positionshown in the figure. only the minus red'vanes' 21 will be interposed inthe path of the light from the lamp Ill, whereas when the system isrotated through approximately 90, only the minus blue vanes 26 will beinterposed in that path. Different percentage compositions of the'colorsminus blue and minus red may be obtained by rotating the systex'n tothecorresponding angular position between these two limits. It will beunderstood, of course, that the filter 26 may be replaced by a suitablysupported layer fluorescent material which emits minus blue, while thefllter 21 may be similarly replaced by fluorescent material which emitsminus red. In this case, the lamp it will, of course, take the form of aclear glass discharge tube which emits light capable of exciting thefluorescent material on the vanes.

It will be understood that many modifications o1 theafore-describedsystem will occur to those skilled in the art to which it appertains.For example, the color filter may comprise more than two colors and thefllter members II and the vanes 28 and 21 broken into a correspondingnumber of sections to provide the additional colors. Father, manymodifications of the gearing system and the supports may be used. Itwill also be understood that the described apparatus may be used foreither contact printing or for enlarging apparatus. In the latter case,suitable light condensing means may be provided. All such modificationsI aim to include within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an apparatus for controlling the color composition of photographicprinting light, a source of radiation capable of exciting fluorescentmaterials, fluorescent means for converting said radiation into eitherone of at least two separate colors and means associated with saidfirstmentioned means for causing it to project in a given directionlight of only one or the other or said colors or for mixing said primarycolors in varying proportions.

2; In an apparatus for controlling the color composition of photographicprinting light, a tubular source of radiation capable of excitingfluorescent materials, rotatable tubular members having at least twolongitudinally extending sections with fluorescent materials thereoncapable of emitting difl'erent colors when excitedJiy said radiationsurrounding said source, means for rotating said members whereby therelative amounts of said colors in the light output at a predeterminedsurface in the field of said source may be varied.

3. In an apparatus for controlling the color composition of photographicprinting light, a source of radiation capable of exciting fluorescentmaterials, rotatable members having at least two sections withfluorescent materials thereon capable of emitting different colors whenexcited by said radiation surrounding said source, means for rotatingsaid members whereby the relative amounts of said colors in the lightoutput at a predetermined surface in the field 01' said source maybevaried from light of either color alone to any desired combination ofthe two colors, and difiusing means interposed between said rotatablemembers and said surface whereby the lilumination at said surface isrendered uniform.

4. In an apparatus for controlling the color composition of(photographic printing light, a photographic plate, a tubular source ofradiation capable of exciting fluorescent materials, a rotatable,cylindrical member having longitudinally disposed sections coated withfluorescent materials capable of fluorescing with different colorsconcentrically surrounding said source and interposed between saidsource and said plate, diflusing means between said member and saidplate, and means for rotating said member whereby the relativ amounts ofsaid colors in the illumination at said diiiusing surface may be variedfrom light of either color alone to any desired combination of the twocolors.

5. man apparatus for controlling the color composition of photographicprinting light, a source of polychromatic light, a plurality of illterscomprising interlocking rotatable vanes oi at least two colorsinterposed in the path of the rays from said source, means for rotatingsaid vanes whereby the relative amounts of said colors in the light at apredetermined surface in the fleld of said source may be varied fromlight of either color alone to any desired combination of the twocolors.

6. In a'n"apparatus for controlling the color composition ofphotographic printing light, a photographic plate, a tubular source ofpolychromatic light, reflector means for directing radiation from saidsource in the direction oi said plate, a plurality of filters comprisinginterlocking rotatable vanes or at least two colors interposed in thepath otsaid rays, and means for rotating said vanes whereby the relativeamounts of said colors in the light impinging upon said photographicplate may be varied from light of either color alone to any desiredcombination of the two colors.

7. In an apparatus for controlling the color composition of photographicprinting light, a photographic plate, a source of radiation capable ofexciting fluorescent materials, reflector means" for directing theradiation from said source in the direction of said plate, a pluralityof interlocking rotatable vanes coated with fluorescent materialscapable of emitting different colors interposed in the path of saidrays, and means for rotating said vanes whereby the relative amounts ofsaid colors in the light impinging upon said photographic plate may bevaried from light of either color alone to any desired combination ofthetwo colors.

8. In an apparatus for controlling the color composition of photographicprinting light, a photographic plate, a tubular source 01 polychromaticlight, reflector means for directing radiation from said source in thedirection of saidplate, a plurality of filters comprising interlockingrotatable vanes 01 at least two colors interposed in the path of saidrays, and means for rotating said vanes whereby the relative amounts ofsaid colors in the light impinging upon said photographic plate may bevaried from light of either color alone to any desired combination ofthe two colors, and difiusing means for rendering the illumination onsaid plate uniform interposed between said vanes and said plate.

9. In an apparatus for controlling the color composition of photographicprinting light, a photographic plate, a source of radiation capable ofexciting fluorescent materials, reflector means for directing theradiation from said source in the direction of said plate, a pluralityof interlocking rotatable vanes having fluorescent materials capable ofemitting diii'erent colors interposed in the path of said rays, andmeans for rotating said vanes amounts of said colors in the lightimpinging upon said photographic plate may be varied from light ofeither color alone to any desired combination of the two colors, anddiffusing means for rendering the illumination interposed between saidplate and said vanes.

EDWARD B. NOEL.

whereby the relativeon said plate uniform

